Why is my image sequence render using an old version of my animation?
I think reason you are seeing an old version of your animation is because you have an image loaded into the Video Sequence Editor (VSE), which is overriding the render. 

Either remove the image strip with X > Erase Strips from the VSE:



Or, un-check 'Sequencer' in the 'Post Processing' panel in the 'Render' tab: